Optical fibers are fusion-spliced to each other by a fusion-splicing apparatus by removing fiber coatings of end portions to be fusion-spliced of the optical fibers, butting end portions of bare glass fibers which are exposed against each other, and heating and fusing the butted end portions to fusion-splice the end portions together. The bare fiber portions which are fusion-spliced to each other are protected by a reinforcing member because the fusion-spliced portions are in a state where the fiber coatings are removed away, and have a low mechanical strength. As the reinforcing member, usually, a reinforcing sleeve is used in which a tensile strength member (also referred to as a reinforcing rod) and a heat-fusible adhesive resin material are housed in a heat-shrinkable tube that is radially shrinkable. The reinforcing sleeve is caused to heat shrink to protect the fusion-spliced portion of the optical fiber.
A usual reinforcement process on a fusion-spliced portion of an optical fiber is performed by a reinforcement processing apparatus comprising a heating heater. A time period required for a work of fusion-splicing optical fibers is 10 to 20 seconds. By contrast, a time period required for a heating process work for reinforcement is 30 to 135 seconds. Even when the fusion-splicing work is rapidly performed, therefore, the subsequent heating process work requires a prolonged time period, and hence the working efficiency of the total fusion-splicing process is hardly improved.
By contrast, for example, Patent Reference 1 discloses a technique in which the heating amount of a heating heater is increased as compared to a usual one, and the temperature rise is suppressed by an air blower disposed below the heater, whereby the heating time period is shortened, and forced cooling is performed by the air blower to shorten the cooling time period, so that the total working time period is shortened.
Patent Reference 2 discloses a technique in which, when the external air temperature is low, a long time period is required for raising the temperature to a predetermined processing temperature, and hence the temperature of a heater and the external air temperature are detected, and, in the case where the external air temperature is low, the heating amount of the heater is increased.
Patent Reference 3 discloses a technique in which, in the case where a reinforcing sleeve is heated by a reinforcement processing apparatus, heating is performed from a middle portion of the sleeve toward both end portions so that voids do not remain inside, and heating at start of a heating process is concentrated to a middle portion of a heater to raise the temperature, thereby shortening the heating time period.    Patent Reference 1: JP-UM-A-4-24705    Patent Reference 2: JP-UM-A-2-73602    Patent Reference 3: Japanese Patent No. 3,293,594